Massive amounts of data storage are required for many emerging and existing applications. For example, video-on-demand applications can provide access to hundreds or thousands of movies for hundreds or thousands of users simultaneously, requiring vast amounts of digital storage, fast access, 24 hours-per-day and 7 days per week (24/7) availability and uptime, and huge bandwidth. Modem supercomputers also require these features, as well as requiring even faster access, extraordinary data integrity, error checking and error correction.
Semiconductor memories provide very fast access, reasonable densities, and moderate costs. However, most common semiconductor memories are volatile (they lose their data when not powered or not refreshed on a timely basis), they develop soft errors (errors that can be corrected by re-writing the affected location) due to various causes including alpha radiation, and they can be cost prohibitive. Additionally, the heat and power requirements can be problematic, if they are used to store vast amounts of information for long time periods.
Hard-disk drives (HDDs, also called just “disk drive” or “drive”)) provide cost-effective non-volatile data storage on rotating media. Data are written and read by magnetic transducer heads that are moved to one of thousands of tracks to locate requested data. There are time penalties incurred to move the head to the requested track, to rotate the disk to the requested location on that track, and to serially read or write the data from or to the track location. The moving parts of a disk drive are prone to wear and failure over time. For applications requiring high reliability (error-free data) and availability (24/7 uptime), data can be stored in a redundant manner (e.g., redundant arrays of inexpensive disks, or RAID), and several different RAID schemes are known to the art, frequently making compromises between performance, cost, and data recoverability. Another requirement for many applications is serviceability—the ease of repairing a faulty system in the field (i.e., at a customer's location of the equipment).
Data storage servers (enclosures having one or more disk drives as well as a data processor to receive data access requests and control the storing and fetching of data to and from the disk drives) and storage vaults (enclosures having one or more disk drives but essentially no processor, and using a data processor housed in a separate enclosure to receive data access requests and control the storing and fetching of data to and from the disk drives) can be implemented in free-standing units (typically an upright unit placed on the floor or on a desk) or as rack-mount units (typically horizontally-oriented units bolted to a standardized nineteen-inch (48.26 cm) rack).
Typical conventional rack-mount disk-drive enclosures arrange a plurality (3 to 14) HDDs in removable carriers that are accessible from the “front” of the unit (the side typically facing a user area), and usually are arranged so that data and power cables are accessible from the “back” of the unit. The disk drives can thus be replaced fairly easily if one were to fail. RAID solutions can be utilized to use redundant data artifacts to compute the data that was on the failed disk drive. This data is sent to a requester or used to recreate the data on a new (spare) disk drive once one is inserted to replace the failed unit. Since racks of rack-mount units are often installed in rows, there is typically no access provided from the sides of a rack-mount unit, and since the rack-mount units are stacked one on top of another in each rack there is typically no access provided from the top or bottom of a rack-mount unit.
High-density packaging of HDDs in an enclosure exacerbates drive-to-drive vibration interaction problems. With several HDDs, packaged closely together in single enclosure, potentially many doing simultaneous head-seeks, the vibration interaction problem is greatly increased. Previous systems and methods to package HDDs and reduce drive-to-drive vibration interaction involved mechanical stiffening of the enclosure and/or lower density packaging options.
Numerous computer applications utilize multiple disk drives for data storage and acquisition. These multiple disk drives are often located in separated locations. For example, disk drives may be arranged in rack systems that consume large amounts of space and require multiple cabinets to house the rack systems. Furthermore, positioning multiple disk drives in separate locations adds to the complexity of data acquisition from the disk drives because a more complex interface with the multiple disk drives is required. In addition, longer cabling is required to reach the separately located disk drives. Accordingly, what is needed is an apparatus that positions multiple disk drives in a manner that simplifies data acquisition from the disk drives and reduces the space needed to house the multiple disk drives.